and disconnect the filling loop it could be leaking past the mickey mouse valves usually fitted to them , and slowly pressurising the system. Doesn`t look bad for a block of Council flats
If you need to find a tradesperson to get your job done, please try our local search below,
or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Please select a service and enter a location to continue...
Are you a trade or supplier? You can create your listing free at DIYnot Local